The present invention relates to an apparatus and method for purifying materials. More particularly, the present invention relates to a method and system for purifying metallurgical silicon fields to produce raw materials suitable for manufacturing single crystal silicon ingots and poly crystal silicon ingots for solar cells at a lower cost. Although the above has been described in terms of purifying silicon, it can be applied to other applications.
Conventional polysilicon silicon material used for manufacturing solar cells is often produced by the so-called Siemens process. Such process is well established, stable, and produces silicon with certain quality for manufacturing solar cells. The Siemens process, however, has limitations. That is, the Siemens' process, due to the nature of its manufacturing process, is difficult to adjust and has failed to meet the dramatic increase in demand and the need for lower prices over the past few years. In addition, it involves use of poisonous raw materials such as HCl and SiHCl3 during the manufacturing process and produces a poisonous by-product, SiCl4. These materials are also highly explosive. The Siemens process is also dangerous and not environmentally friendly.
Alternatively, silicon purification methods that use metallurgy have been proposed. Such purification methods, however, have limitations. That is, such methods have not been able to achieve production scale. Certain other efforts have been achieved using metallurgy techniques. Unfortunately, the ability to scale of the equipment for such techniques is enormous, and thus the production costs are still high. These and other limitations may be overcome by the present techniques described throughout the present specification and more particularly below.
From the above, it is seen that improved techniques for producing silicon are highly desired.